The present invention relates to compositions and methods of making asphaltic concrete.
Asphaltic concrete is a commonly used paving material for roads, parking lots, etc. Asphaltic concrete is also referred to as xe2x80x9cblacktopxe2x80x9d, xe2x80x9cbituminous concretexe2x80x9d or simply as xe2x80x9casphaltxe2x80x9d and is made up of an asphalt cement or binder and an aggregate. The asphalt cement permeates the voids between the individual pieces and particles of aggregate, binding the whole in a cementatious mass. Asphaltic concrete is readily workable, especially when heated (as in hot mix asphaltic concrete). The material can be compacted and rolled to provide a smooth surface. In addition, the asphaltic concrete serves as a barrier to water, thereby protecting the subgrade.
Unpaved dirt roads exhibit rutting and may even be washed out in heavy rains. Paving a road with asphaltic concrete extends the life of the road driving surface and allows relatively high vehicular traffic. The road driving surface retains a smoothness suitable for wheeled vehicles traveling at moderate to high speeds. Asphaltic concrete is less expensive than nonasphaltic concrete.
Roads paved with asphaltic concrete have a tendency to rut after being subjected to vehicular traffic. Rutted asphalt roads require maintenance and periodic replacement. One of the causes of rutting is the application of shear forces to the asphaltic concrete layer by vehicle tires. The shearing behavior of asphaltic concrete can be predicted with the Mohr-Coulomb Theory, as represented by the following equation:
xcfx84=c+"sgr" (tan xcfx86)
where, xcfx84 is the shear strength of the mixture
c is cohesion
"sgr" is normal stress
xcfx86 is the angle of internal friction of the aggregate. Thus, the higher the cohesion of the asphalt binder and/or the higher the internal friction of the aggregate, the greater the shear strength and the more resistance to rutting in the paved surfaces.
It is desired to provide an asphaltic concrete that exhibits less rutting.
It is an object of the present invention to provide an asphaltic concrete composition that requires less maintenance than prior art compositions.
It is another object of the present invention to provide an asphaltic concrete composition that resists rutting.
The present invention provides a method of making asphaltic concrete. Sulfuric acid, citrus stripper oil and asphalt cement are mixed together to form an asphalt mixture. The asphalt mixture is mixed with an aggregate.
In accordance with one aspect of the present invention, the step of mixing the asphalt mixture with the aggregate further comprises heating the asphalt mixture before mixing with the aggregate.
In accordance with still another aspect of the present invention, after the asphalt mixture is mixed with the aggregate, the asphalt mixture is applied to a ground.
In accordance with another aspect of the present invention, the asphalt mixture is packed in place on the ground.
The present invention also provides a composition for use in paving roads. The composition comprises an asphalt cement and sulfuric acid and citrus stripper oil mixed with the asphalt cement.
The present invention also provides an asphaltic concrete composition comprising a packed and consolidated admixture of aggregate, asphalt cement, sulfuric acid and citrus stripper oil.